COMPRESSOR

Abstract

 A compressor subjects a fluid compressed by a first impeller to further compression by a second impeller. The compressor includes an impeller housing including a first housing accommodating the first impeller, and a second housing accommodating the second impeller, and an interstage component coupled to the impeller housing, and forming, together with the impeller housing, an interstage passage configured to introduce the fluid from the first impeller into the second impeller. The interstage passage includes at least one curved passage. The curved passage includes an inner wall surface that is curved on an inner side in a cross-section passing through a center line of the curved passage, and an outer wall surface that is curved on an outer side in the cross-section. One of the inner wall surface and the outer wall surface is formed in the impeller housing. Another of the inner wall surface and the outer wall surface is formed in the interstage component.

Description

Technical Field

[0001] The present disclosure relates to a compressor.

Background Art

[0002] Patent Literatures 1 to 3 disclose techniques relating to compressors. As such compressors, a multistage compressor including two or more compression stages are known. A multistage compressor includes, for example, a former compression stage that intakes and compresses a fluid, and a latter compression stage that further compresses the fluid compressed in the former compression stage. Generally, in such a multistage compressor, the former compression stage is connected to the latter compression stage by a pipe, and the fluid from the former compression stage is introduced into the latter compression stage through a passage inside the pipe.

Citation List

Patent Literature

[0003] 

[Patent Literature 1] WO 2021/038737

[Patent Literature 2] Japanese Unexamined Patent Publication No. 2012-202331

[Patent Literature 3] Japanese Unexamined Patent Publication No. 2021-085512

Summary of Invention

Technical Problem

[0004] However, the configuration in which the former compression stage is connected to the latter compression stage by a pipe requires man-hours for assembling the pipe to the compression stages. Furthermore, there is the cost for the assembly man-hours in addition to the cost of the pipe itself, so that mass production cost tends to be high. Consequently, it is difficult to improve productivity of the compressor with the configuration above.

[0005] The present disclosure describes a compressor that is capable of improving productivity.

Solution to Problem

[0006] A compressor according to an embodiment of the present disclosure is configured to subject a fluid compressed by a first impeller to further compression by a second impeller. The compressor includes an impeller housing including a first housing accommodating the first impeller, and a second housing accommodating the second impeller, and an interstage component coupled to the impeller housing, and forming, together with the impeller housing, an interstage passage configured to introduce the fluid from the first impeller into the second impeller. The interstage passage has at least one curved passage. The curved passage includes an inner wall surface that is curved on an inner side in a cross-section passing through a center line of the curved passage, and an outer wall surface that is curved on an outer side in the cross-section. One of the inner wall surface and the outer wall surface is formed in the impeller housing. Another of the inner wall surface and the outer wall surface is formed in the interstage component.

Advantageous Effects of Invention

[0007] Some embodiments of the present disclosure provide a compressor that is capable of improving productivity.

Brief Description of Drawings

[0008] 

FIG. 1 is a cross-sectional view illustrating a compressor according to an embodiment.

FIG. 2 is an enlarged cross-sectional view of a compression unit of the compressor of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of a portion of an interstage passage of the compression unit of FIG. 1.

FIG. 4(a) is a cross-sectional view of the interstage passage taken along line A1-A1 of FIG. 3. FIG. 4(b) is a cross-sectional view of the interstage passage taken along line A2-A2 of FIG. 3.

FIG. 5 is a cross-sectional view illustrating the compression unit of FIG. 2 with components of the compression unit being divided.

FIG. 6 is an enlarged cross-sectional view of a compression unit according to a comparative example.

FIG. 7(a) is an enlarged cross-sectional view of a portion of a compression unit according to Reference Example 1. FIG. 7(b) is an enlarged cross-sectional view of a portion of a compression unit according to Reference Example 2.

FIG. 8(a) is an enlarged cross-sectional view of a portion of a compression unit according to Reference Example 3. FIG. 8(b) is an enlarged cross-sectional view of a portion of a compression unit according to Reference Example 4.

FIG. 9 is an enlarged cross-sectional view of a portion of a compression unit according to Variation 1.

FIG. 10 is an enlarged cross-sectional view of a portion of a compression unit according to Variation 2.

Description of Embodiments

[0009] A compressor according to an embodiment of the present disclosure is configured to subject a fluid compressed by a first impeller to further compression by a second impeller. The compressor includes an impeller housing including a first housing accommodating the first impeller, and a second housing accommodating the second impeller, and an interstage component coupled to the impeller housing, and forming, together with the impeller housing, an interstage passage configured to introduce the fluid from the first impeller into the second impeller The interstage passage has at least one curved passage. The curved passage includes an inner wall surface that is curved on an inner side in a cross-section passing through a center line of the curved passage, and an outer wall surface that is curved on an outer side in the cross-section. One of the inner wall surface and the outer wall surface is formed in the impeller housing. Another of the inner wall surface and the outer wall surface is formed in the interstage component.

[0010] In the compressor above, the interstage passage that introduces the fluid from the first impeller into the second impeller is formed by the impeller housing and the interstage component. One of the inner wall surface and the outer wall surface of the curved passage of the interstage passage is formed in the impeller housing, and the other of the inner wall surface and the outer wall surface is formed in the interstage component. That is, the inner wall surface and the outer wall surface of the curved passage are formed in different housings. In this case, unlike in a case in which the inner wall surface and the outer wall surface are formed in one housing, the forming of an overhanging portion in each component can be avoided, which enables demolding of the components. This enables each component to be formed by die-casting, which has a low production cost. Furthermore, in the configuration above, steps such as preparing a separate pipe for the configuration of the interstage passage and assembling the pipe to the impeller housing can be omitted, so that the assembly man-hours can be reduced. Consequently, the compressor above is capable of improving productivity and suppressing mass production cost.

[0011] In some embodiments, a border line indicating a boundary between the impeller housing and the interstage component in the cross-section may have a first border line and a second border line between the inner wall surface and the outer wall surface. The first border line may extend to intersect a straight line connecting a starting end of the inner wall surface to a starting end of the outer wall surface. The second border line may extend to intersect a straight line connecting a terminal end of the inner wall surface to a terminal end of the outer wall surface. The second border line may be directly or indirectly connected to the first border line between the inner wall surface and the outer wall surface. In this case, the border line can be set to match the shapes of the inner wall surface and the outer wall surface, which eliminates the need to make adjustments such as changing the shapes of the inner wall surface and the outer wall surface to match the border line. As a result, it is possible to avoid the occurrence of situations in which changes occur in each passage cross-section of the curved passage with the change in the shapes of the inner wall surface and the outer wall surface. This makes it possible to suppress situations in which pressure loss occurs in the fluid that flows through the curved passage, and to suppress reduction in the performance of the compressor.

[0012] In some embodiments, a distance between the inner wall surface and the outer wall surface in a direction perpendicular to the center line may be constant at each position along the center line. In this case, situations in which changes occur in the cross-sectional area of each passage cross-section of the curved passage can be suppressed. This makes it possible to suppress situations in which pressure loss occurs in the fluid that flows through the curved passage, and to suppress reduction in the performance of the compressor.

[0013] In some embodiments, in a cross-section perpendicular to the center line of the curved passage, the inner wall surface may extend linearly. The outer wall surface may be curved so as to expand from the inner wall surface in a direction opposite the inner wall surface. This facilitates die-casting with the direction from the outer wall surface toward the inner wall surface as a demolding direction.

[0014] In some embodiments, the interstage component may be an interstage housing coupled in series to the first housing via the second housing. The inner wall surface may be formed in the second housing. The outer wall surface may be formed in the interstage component. In this case, the forming of the interstage passage is facilitated by the simple operation of coupling the interstage housing, the second housing, and the first housing in series. Furthermore, the second housing and the interstage housing can be demolded by the inner wall surface and the outer wall surface being separately formed in the second housing and the interstage component in this way.

[0015] In some embodiments, the interstage component may be an interstage plate sandwiched between the first housing and the second housing. The inner wall surface may be formed in the interstage component. The outer wall surface may be formed in the first housing. In this case, the forming of the interstage passage is facilitated by utilizing the interstage plate between the first housing and the second housing. Furthermore, the interstage plate and the first housing can be demolded by the inner wall surface and the outer wall surface being separately formed in the interstage plate and the first housing in this way.

[0016] In some embodiments, a first wall surface and a second wall surface may extend parallel to each other in the cross-section passing through the center line, and may be formed in the impeller housing. In this case, the impeller housing in which a linear passage is formed can be demolded by setting the direction in which the linear passage extends as the demolding direction. Consequently, the components can be demolded even with such interstage passage that has the curved passage and the linear passage.

[0017] Embodiments of the present disclosure will be described below with reference to the drawings. Same reference signs are given to the same elements in the description of the drawings, and redundant description will be omitted as appropriate.

[0018] A compressor 1 illustrated in FIG. 1 is, for example, a series two-stage compressor. The compressor 1 includes a shaft 10, a compression unit 30, and a motor unit 50. The compression unit 30 has a first impeller 31, a second impeller 32, and an impeller housing 33. The first impeller 31 and the second impeller 32 are attached to one end portion of the shaft 10. The first impeller 31 and the second impeller 32 are, for example, disposed such that rear surfaces thereof face each other with a gap therebetween. The first impeller 31 is, for example, disposed coaxial with the second impeller 32. The first impeller 31 is, for example, positioned between the second impeller 32 and the motor unit 50.

[0019] The impeller housing 33 has a first housing 41 that accommodates the first impeller 31, and a second housing 42 that accommodates the second impeller 32. The second housing 42 is connected in series to the first housing 41 in an axial direction D1 in which the shaft 10 extends. The first impeller 31 and the first housing 41 form a low pressure-side compression stage that intakes and compresses a fluid R. The second impeller 32 and the second housing 42 form a high pressure-side compression stage that further compresses the fluid R compressed by the low pressure-side compression stage.

[0020] The compression unit 30 further has an interstage plate 43 and an interstage housing 44. The interstage plate 43 and the interstage housing 44 are each an interstage component coupled to the impeller housing 33. The interstage plate 43 and the interstage housing 44 form, together with the impeller housing 33, an interstage passage 60 that introduces the fluid R from the first impeller 31 of the low pressure-side compression stage into the second impeller 32 of the high pressure-side compression stage. The interstage plate 43 is a plate-like component sandwiched between the first housing 41 and the second housing 42. The interstage housing 44 is a housing component that is coupled to the second housing 42 on the opposite side from the first housing 41 in the axial direction D1. The interstage housing 44 is coupled in series to the first housing 41 via the second housing 42 and the interstage plate 43 in the axial direction D1. Consequently, the interstage housing 44, the second housing 42, the interstage plate 43, and the first housing 41 are coupled in series to each other in the axial direction D1. The configurations being coupled in series in the axial direction D1 refers to the configurations being arranged in the axial direction D1, and each configuration having a connecting surface that intersects with the axial direction D1. In this embodiment, the interstage plate 43, the first housing 41, and the second housing 42 are members that are separately provided. That is, the interstage plate 43, the first housing 41, and the second housing 42 are separate and independent components. The interstage plate 43, the first housing 41, and the second housing 42 are integrated to form the compression unit 30. A publicly known fastening means such as screws or bolts and nuts, or a publicly known bonding means such as welding or melt-bonding may be used as the means for integrating the interstage plate 43, the first housing 41, and the second housing 42.

[0021] The motor unit 50 has an electric motor 51 and a motor housing 52. The electric motor 51 is a drive source for driving the compression unit 30. The electric motor 51 is attached to the other end portion of the shaft 10. The shaft 10 is rotatably supported by a bearing inside the motor housing 52. The motor housing 52 accommodates the electric motor 51. The motor housing 52 is coupled in series to the first housing 41 in the axial direction D1. The motor housing 52, the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44 are separate and independent components, which are combined to form the housing of the compressor 1.

[0022] FIG. 2 illustrates an enlargement of the compression unit 30. As illustrated in FIG. 2, the first housing 41 includes an inlet 41a, a diffuser passage 41b, and a scroll passage 41c. The inlet 41a is an opening that is coaxial with the shaft 10, and communicates with the inside of the motor housing 52 (see FIG. 1). The fluid R that is sucked in from an inlet of the motor housing 52 flows into the inlet 41a. The first impeller 31 is disposed inward of the inlet 41a. Speed energy is applied to the fluid R by rotation of the first impeller 31. The scroll passage 41c is formed so as to surround the first impeller 31. The diffuser passage 41b is formed between the first impeller 31 and the scroll passage 41c. The diffuser passage 41b compresses the fluid R by converting the speed energy applied to the fluid R into compression energy. The scroll passage 41c discharges the fluid R compressed by the diffuser passage 41b.

[0023] The second housing 42 includes an inlet 42a, a diffuser passage 42b, a scroll passage 42c, and an outlet 42d. The inlet 42a is an opening that is coaxial with the inlet 41a of the first housing 41, and faces away from the inlet 41a. The inlet 42a is connected to the scroll passage 41c of the first housing 41 via the interstage passage 60. The fluid R from the scroll passage 41c thus flows into the inlet 42a via the interstage passage 60. The second impeller 32 is disposed inward of the inlet 42a. Speed energy is applied to the fluid R by rotation of the second impeller 32. The scroll passage 42c is formed so as to surround the second impeller 32. The diffuser passage 42b is formed between the second impeller 32 and the scroll passage 42c. The diffuser passage 42b further compresses the fluid R by converting the speed energy applied to the fluid R into compression energy. The scroll passage 42c externally discharges the compressed fluid R from the outlet 42d.

[0024] The configuration of the interstage passage 60 will next be described in detail. In the following description, "above" and "upward" refer to an upper side in a vertical direction D2 when the compressor 1 is installed in a location of use, and "below" and "downward" refer to a lower side in the vertical direction D2. In this embodiment, the shaft 10 is disposed so as to extend in a horizontal direction when the compressor 1 is installed in a location of use. Consequently, the axial direction D1 is perpendicular to the vertical direction D2 in this embodiment.

[0025] The interstage passage 60 includes, for example, a curved passage 61, a linear passage 62, a curved passage 63, a linear passage 64, and a curved passage 65. These passages are formed on the same plane. That is, a center line CL of these passages are included in the same plane. The same plane here may, for example, be a plane along the axial direction D1 and the vertical direction D2. The center line CL of the interstage passage 60 may be a line that passes through the centroid of each passage cross-section perpendicular to a direction of extension of the interstage passage 60. FIG. 2 illustrates a cross-section of the compression unit 30 when the compression unit 30 is cut such that the cut passes through the center line CL in the plane along the axial direction D1 and the vertical direction D2. In this embodiment, the curved passage 61, the linear passage 62, the curved passage 63, the linear passage 64, and the curved passage 65 that form the interstage passage 60 are disposed in that order from upstream to downstream in a direction of flow of the fluid R that flows through the interstage passage 60.

[0026] The linear passage 62 is positioned below the second impeller 32, and extends in the axial direction D1. For example, the linear passage 62 extends parallel to the shaft 10. The curved passage 61 is positioned below the first impeller 31, and extends so as to be curved in an arc-shape between an exit 41d of the scroll passage 41c and the linear passage 62. That is, the curved passage 61 extends below the exit 41d of the scroll passage 41c, and is curved so as to connect to the linear passage 62 in the axial direction D1. The curved passage 63, the linear passage 64, and the curved passage 65 are positioned on a side of the second impeller 32 opposite that of the first impeller 31 in the axial direction D1.

[0027] The linear passage 64 extends linearly in the vertical direction D2 in a position above the linear passage 62 and below the shaft 10. The curved passage 63 is disposed on a side of the linear passage 62 opposite that of the curved passage 61 in the axial direction D1. The curved passage 63 extends so as to be curved in an arc-shape between the linear passage 62 and the linear passage 64. That is, the curved passage 63 extends upward from the linear passage 62, and is curved so as to connect to the linear passage 64. The curved passage 65 is disposed on a side of the linear passage 62 opposite that of the curved passage 63 in the vertical direction D2. The curved passage 65 extends so as to be curved in an arc-shape between the linear passage 64 and the inlet 42a. That is, the curved passage 65 extends above the linear passage 64, and is curved so as to connect to the inlet 42a in the axial direction D1.

[0028] The curved passage 61, the curved passage 63, and the curved passage 65, for example, have the same curvature. The curvature here may be based on the center line CL of each curved passage. In this embodiment, a "curved passage" refers to a passage that is a continuously curved portion of the interstage passage 60 represented by a curvature in the cross-section illustrated in FIG. 2. The curved passage 61, the curved passage 63, and the curved passage 65 may, for example, have different curvatures. The curved passage 61, the curved passage 63, and the curved passage 65 may be directly connected to each other, and not via a linear passage. As described further below, the curved passage 61, the curved passage 63, and the curved passage 65 of this embodiment are formed by the combination of the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. In this embodiment, the curved passage 61, the curved passage 63, and the curved passage 65 are formed only by curved portions in the cross-section illustrated in FIG. 2. However, the curved passage 61, the curved passage 63, and the curved passage 65 are not limited to this embodiment, and may, for example, include a passage that extends linearly on a starting end or a terminal end, or between the starting end and the terminal end of each curved passage.

[0029] The configuration of each passage of the interstage passage 60 will now be described in detail. The curved passage 61 includes an inner wall surface 61a that forms the wall surface of the curved passage 61 on an inner side, and an outer wall surface 61b that forms the wall surface of the curved passage 61 on an outer side. In the cross-section illustrated in FIG. 2, the inner wall surface 61a and the outer wall surface 61b are represented as arc-shaped curves. The inner wall surface 61a is curved in an arc-shape in a position on the inner side, that is, in a position inward of the outer wall surface 61b in a radial direction. The outer wall surface 61b is curved in an arc-shape in a position on the outer side, that is, in a position outward of the inner wall surface 61a in the radial direction.

[0030] The outer wall surface 61b is, for example, disposed concentric with the inner wall surface 61a, and extends parallel to the inner wall surface 61a. The inner wall surface 61a may be a portion of the wall surface forming the curved passage 61 that at least includes the arc-shaped curved portion on the inner side illustrated in FIG. 2. The outer wall surface 61b may be a portion of the wall surface forming the curved passage 61 that at least includes the arc-shaped curved portion on the outer side illustrated in FIG. 2. The outer wall surface 61b may be the portion excluding the inner wall surface 61a. A starting end Pa of the inner wall surface 61a and a starting end Pb of the outer wall surface 61b are connected to the wall surface that forms the exit 41d of the scroll passage 41c. A starting end of a wall surface herein refers to one end of the wall surface that is positioned upstream in the direction of flow of the fluid R that flows through the interstage passage 60 in the cross-section illustrated in FIG. 2. A terminal end of a wall surface refers to the other end of the wall surface that is positioned downstream in the direction of flow.

[0031] The curved passage 63 includes an inner wall surface 63a that forms the wall surface of the curved passage 63 on the inner side, and an outer wall surface 63b that forms the wall surface of the curved passage 63 on the outer side. In the cross-section illustrated in FIG. 2, the inner wall surface 63a and the outer wall surface 63b are represented as arc-shaped curves. The inner wall surface 63a is curved in an arc-shape in a position on the inner side, that is, in a position inward of the outer wall surface 63b in the radial direction. The outer wall surface 63b is curved in an arc-shape in a position on the outer side, that is, in a position outward of the inner wall surface 63a in the radial direction. The outer wall surface 63b is disposed concentric with the inner wall surface 63a, and extends parallel to the inner wall surface 63a. The inner wall surface 63a may be a portion of the wall surface forming the curved passage 63 that at least includes the arc-shaped curved portion on the inner side illustrated in FIG. 2. The outer wall surface 63b may be a portion of the wall surface forming the curved passage 63 that at least includes the arc-shaped curved portion on the outer side illustrated in FIG. 2. The outer wall surface 63b may be the portion excluding the inner wall surface 63a.

[0032] The curved passage 65 includes an inner wall surface 65a that forms the wall surface of the curved passage 65 on the inner side, and an outer wall surface 65b that forms the wall surface of the curved passage 65 on the outer side. In the cross-section illustrated in FIG. 2, the inner wall surface 65a and the outer wall surface 65b are represented as arc-shaped curves. The inner wall surface 65a is curved in an arc-shape in a position on the inner side, that is, in a position inward of the outer wall surface 65b in the radial direction. The outer wall surface 65b is curved in an arc-shape in a position on the outer side, that is, in a position outward of the inner wall surface 65a in the radial direction. The outer wall surface 65b is disposed concentric with the inner wall surface 65a, and extends parallel to the inner wall surface 65a. The inner wall surface 65a may be a portion of the wall surface forming the curved passage 65 that at least includes the arc-shaped curved portion on the inner side illustrated in FIG. 2. The outer wall surface 65b may be a portion of the wall surface forming the curved passage 65 that at least includes the arc-shaped curved portion on the outer side illustrated in FIG. 2. The outer wall surface 65b may be a portion of the wall surface excluding the inner wall surface 65a. A terminal end P5a of the inner wall surface 65a and a terminal end P5b of the outer wall surface 65b are connected to the wall surface that forms the inlet 42a.

[0033] The linear passage 62 includes a first wall surface 62a that is connected to a terminal end P1a of the inner wall surface 61a and a starting end P2a of the inner wall surface 63a in the axial direction D1, and a second wall surface 62b that is connected to a terminal end P1b of the outer wall surface 61b and a starting end P2b of the outer wall surface 63b in the axial direction D1. In the cross-section illustrated in FIG. 2, the first wall surface 62a and the second wall surface 62b are represented as straight lines extending parallel to each other in the axial direction D1. The first wall surface 62a may be a portion of the wall surface forming the linear passage 62 that corresponds to the inner wall surface 61a and the inner wall surface 63a. The second wall surface 62b may be a portion of the wall surface forming the linear passage 62 that corresponds to the outer wall surface 61b and the outer wall surface 63b. The second wall surface 62b may be a portion of the wall surface excluding the first wall surface 62a.

[0034] The linear passage 64 includes a first wall surface 64a that is connected to a terminal end P3a of the inner wall surface 63a and a starting end P4a of the inner wall surface 65a in the vertical direction D2, and a second wall surface 64b that is connected to a terminal end P3b of the outer wall surface 63b and a starting end P4b of the outer wall surface 65b in the vertical direction D2. In the cross-section illustrated in FIG. 2, the first wall surface 64a and the second wall surface 64b are represented as straight lines extending parallel to each other in the vertical direction D2. The first wall surface 64a may be a portion of the wall surface forming the linear passage 64 that corresponds to the inner wall surface 63a and the inner wall surface 65a. The second wall surface 64b may be a portion of the wall surface forming the linear passage 64 that corresponds to the outer wall surface 63b and the outer wall surface 65b. The second wall surface 64b may be a portion of the wall surface excluding the first wall surface 64a.

[0035] The area of each passage cross-section of the interstage passage 60 is, for example, constant. That is, the area of the passage cross-section of the interstage passage 60 at any position along the center line CL is set to be the same as the area of the passage cross-section of the interstage passage 60 at any other position along the center line CL. Consequently, the cross-sectional area of the linear passage 62, the cross-sectional area of the linear passage 64, the cross-sectional area of the curved passage 61, the cross-sectional area of the curved passage 63, and the cross-sectional area of the curved passage 65 are the same. The cross-sectional areas of the passages being the same is not limited to cases in which the cross-sectional areas of the passages are exactly the same, and the cross-sectional areas of the passages may include a certain amount of allowable error. A certain amount of allowable error refers, for example, to an error in the cross-sectional areas of the passages within an acceptable range for pressure loss that occurs in the fluid R that flows through the passage.

[0036] FIG. 3 illustrates an enlargement of the vicinity of the curved passage 63 of the interstage passage 60. In the case in which the cross-sectional area of the curved passage 63 is constant, the distance between the outer wall surface 63b and the inner wall surface 63a is a constant distance d at each position along a direction of extension of the center line CL. That is, the distance between the outer wall surface 63b and the inner wall surface 63a at any position along the center line CL is the same as the distance between the outer wall surface 63b and the inner wall surface 63a at any other position along the center line CL (i.e., constant distance d). The distance between the outer wall surface 63b and the inner wall surface 63a refers to the gap between the outer wall surface 63b and the inner wall surface 63a in a direction perpendicular to the center line CL in the cross-section illustrated in FIG. 3. The distance between the first wall surface 62a and the second wall surface 62b of the linear passage 62, the distance between the first wall surface 64a and the second wall surface 64b of the linear passage 64, the distance between the outer wall surface 61b and the inner wall surface 61a of the curved passage 61, and the distance between the outer wall surface 65b and the inner wall surface 65a of the curved passage 65 may also be the constant distance d at each position along the direction of extension of the center line CL.

[0037] The shapes of the passage cross-sections of the interstage passage 60 are, for example, the same. FIG. 4(a) illustrates a cross-sectional shape of the curved passage 63 in a plane perpendicular to the center line CL. As illustrated in FIG. 4(a), the cross-sectional shape of the curved passage 63 is not circular, but U-shaped. The inner wall surface 63a that forms the curved passage 63 extends linearly in the cross-section illustrated in FIG. 4(a). Consequently, the inner wall surface 63a forms a plane that extends in a direction along the center line CL and the direction perpendicular to the center line CL. The outer wall surface 63b is curved so as to expand away from the inner wall surface 63a in the cross-section illustrated in FIG. 4(a). Consequently, the outer wall surface 63b forms a curved plane that extends along the direction along the center line CL and is curved in the direction perpendicular to the center line CL.

[0038] The outer wall surface 63b includes, in the cross-section illustrated in FIG. 4(a), an arc-shaped curved portion P11 that is curved so as to expand away from the inner wall surface 63a, and a pair of linear portions P12, P13 that connect the curved portion P11 to the inner wall surface 63a. The pair of linear portions P12, P13 extend linearly in a direction perpendicular to the inner wall surface 63a from respective ends of the inner wall surface 63a, and are connected to respective ends of the curved portion P11. The pair of linear portions P12, P13, for example, extend parallel to each other. The curved passage 61 and the curved passage 65 also have the same cross-sectional shape as the curved passage 63.

[0039] FIG. 4(b) illustrates a cross-sectional shape of the linear passage 62 in the plane perpendicular to the center line CL. As illustrated in FIG. 4(b), the linear passage 62, for example, has the same cross-sectional shape as the curved passage 63. The first wall surface 62a that forms the linear passage 62 extends linearly in the cross-section illustrated in FIG. 4(b). Consequently, the first wall surface 62a forms a plane that extends in the direction along the center line CL and the direction perpendicular to the center line CL, similarly to the inner wall surface 63a. The second wall surface 62b is curved so as to expand away from the first wall surface 62a in the cross-section illustrated in FIG. 4(b). Consequently, the second wall surface 62b forms a curved plane that extends along the direction along the center line CL and is curved in the direction perpendicular to the center line CL, similarly to the outer wall surface 63b.

[0040] The second wall surface 62b includes, in the cross-section illustrated in FIG. 4(b), an arc-shaped curved portion P21 that is curved so as to expand away from the first wall surface 62a, and a pair of linear portions P22, P23 that connect the curved portion P21 to the first wall surface 62a. The pair of linear portions P22, P23 extend linearly in a direction perpendicular to the first wall surface 62a from respective ends of the first wall surface 62a, and are connected to respective ends of the curved portion P21. The pair of linear portions P22, P23, for example, extend parallel to each other. The linear passage 64 also has the same cross-sectional shape as the linear passage 62.

[0041] As described above, the interstage passage 60 having the configuration above is formed by the combination of the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. That is, the wall surface that forms the interstage passage 60 is separately formed in the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. The cross-section illustrated in FIG. 2 shows border lines L1, L2, L3 indicating the boundaries between the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44. The border line L1 indicates the boundary between the first housing 41 and the interstage plate 43. The border line L2 indicates the boundary between the interstage plate 43 and the second housing 42. The border line L3 indicates the boundary between the second housing 42 and the interstage housing 44.

[0042] The border line L1 extends in the vertical direction D2 so as to pass through the curved passage 61 of the interstage passage 60. The border line L1 includes a border line L11, a border line L12, and a border line L13. The border line L11 extends in the vertical direction D2 between the starting end Pa of the inner wall surface 61a and the starting end Pb of the outer wall surface 61b. For example, the border line L11 extends in the vertical direction D2 so as to be in contact with the starting end Pa of the inner wall surface 61a. The border line L11 passes through the scroll passage 41c. A lower end of the border line L11 is, for example, positioned between the inner wall surface 61a and the center line CL.

[0043] The border line L13 extends in the vertical direction D2 below the border line L11 in a position offset from the border line L11 in the axial direction D1. The border line L13, for example, extends in the vertical direction D2 so as to be in contact with the terminal end P1b of the outer wall surface 61b, or so as to pass through the terminal end P1b. An upper end of the border line L13 is, for example, in the same position as the lower end of the border line L11 in the vertical direction D2. The border line L12 connects the lower end of the border line L11 to the upper end of the border line L13 in the axial direction D1. The border line L12 extends in the axial direction D1 between the terminal end P1a of the inner wall surface 61a and the terminal end P1b of the outer wall surface 61b, more specifically, between the terminal end P1a of the inner wall surface 61a and the center line CL. The border line L12 may, for example, extend in the axial direction D1 so as to be in contact with the terminal end P1a of the inner wall surface 61a. As a result of such border line L1 being set, the entirety of the inner wall surface 61a from the starting end Pa to the terminal end P1a is disposed on one side of the border line L1. The entirety of the outer wall surface 61b from the starting end Pb to the terminal end P1b is disposed on the other side of the border line L1.

[0044] The border line L2 is positioned between the border line L1 and the border line L3, and extends in the vertical direction D2 so as to pass through the linear passage 62 of the interstage passage 60. The border line L2 includes a border line L21 and a border line L22. The border line L21 extends parallel to the border line L11 and the border line L13 with gaps therebetween. The border line L21 extends in the vertical direction D2 so as to pass through the scroll passage 42c. The border line L22 extends in the axial direction D1 from an upper end of the border line L21, and is connected to the border line L11 of the border line L1.

[0045] The border line L3 extends in the vertical direction D2 so as to pass through the curved passage 63 and the curved passage 65 of the interstage passage 60. The border line L3 includes a border line L31 (first border line), a border line L32 (second border line), a border line L33, a border line L34, and a border line L35. The border line L31 extends in the vertical direction D2 between the terminal end P3a of the inner wall surface 63a and the terminal end P3b of the outer wall surface 63b. For example, the border line L31 extends in the vertical direction D2 so as to be in contact with the terminal end P3a of the inner wall surface 63a. A lower end of the border line L31 is, for example, positioned between the inner wall surface 63a and the center line CL. The border line L31 extends in the vertical direction D2 between the starting end P4a of the inner wall surface 65a and the starting end P4b of the outer wall surface 65b. For example, the border line L31 extends in the vertical direction D2 so as to be in contact with the starting end P4a of the inner wall surface 65a. The lower end of the border line L31 is, for example, positioned between the inner wall surface 63a and the center line CL. An upper end of the border line L31 is, for example, positioned between the inner wall surface 65a and the center line CL.

[0046] The border line L33 extends in the vertical direction D2 below the border line L31 in a position offset from the border line L31 toward the border line L2 in the axial direction D1. The border line L33, for example, extends in the vertical direction D2 so as to be in contact with the starting end P2b of the outer wall surface 63b, or so as to pass through the starting end P2b. An upper end of the border line L33 is, for example, in the same position as the lower end of the border line L31 in the vertical direction D2. The border line L32 connects the lower end of the border line L31 to the upper end of the border line L33 in the axial direction D1. The border line L32 extends in the axial direction D1 between the starting end P2a of the inner wall surface 63a and the starting end P2b of the outer wall surface 63b, more specifically, between the starting end P2a of the inner wall surface 63a and the center line CL. The border line L32 may, for example, extend in the axial direction D1 so as to be in contact with the starting end P2a of the inner wall surface 63a.

[0047] The border line L34 extends in the vertical direction D2 above the border line L31 in a position offset from the border line L31 toward the border line L2 in the axial direction D1. The border line L34, for example, extends in the vertical direction D2 so as to be in contact with the terminal end P5b of the outer wall surface 65b, or so as to pass through the terminal end P5b. A lower end of the border line L34 is, for example, in the same position as the upper end of the border line L31 in the vertical direction D2. The border line L35 connects the upper end of the border line L31 to the lower end of the border line L34 in the axial direction D1. The border line L35 extends in the axial direction D1 between the terminal end P5a of the inner wall surface 65a and the terminal end P5b of the outer wall surface 65b, more specifically, between the terminal end P5a of the inner wall surface 65a and the center line CL. The border line L35 may, for example, extend in the axial direction D1 so as to be in contact with the terminal end P5a of the inner wall surface 65a.

[0048] As a result of such border line L3 being set, the entirety of the inner wall surface 63a from the starting end P2a to the terminal end P3a is disposed on one side of the border line L3. The entirety of the outer wall surface 63b from the starting end P2b to the terminal end P3b is disposed on the other side of the border line L3. The entirety of the inner wall surface 65a from the starting end P4a to the terminal end P5a is disposed on the one side of the border line L3. The entirety of the outer wall surface 65b from the starting end P4b to the terminal end P5b is disposed on the other side of the border line L3.

[0049] FIG. 5 illustrates the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44 being divided from each other at the border lines L1, L2, L3. As illustrated in FIG. 5, the border line L1 that passes through the curved passage 61 divides the inner wall surface 61a and the outer wall surface 61b of the curved passage 61. As a result, the outer wall surface 61b (i.e., the entirety of the outer wall surface 61b from the starting end Pb to the terminal end P1b) positioned on one side of the border line L1 is formed in the first housing 41. The inner wall surface 61a (i.e., the entirety of the inner wall surface 61a from the starting end Pa to the terminal end P1a) positioned on the other side of the border line L1 is formed in the interstage plate 43. That is, the inner wall surface 61a and the outer wall surface 61b that form the wall surface of the curved passage 61 are separately formed in the interstage plate 43 and the first housing 41, respectively.

[0050] The first housing 41 includes divided surfaces S11a, S12a, and S13a that are formed by being divided at the border line L1. The divided surface S11a is a plane that is formed due to a division at the border line L11, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S13a is a plane that is formed due to a division at the border line L13, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S13a is, for example, offset toward the linear passage 62 in the axial direction D1 relative to the divided surface S11a. The divided surface S12a is a plane that is formed due to a division at the border line L12, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S12a connects the divided surface S11a to the divided surface S13a in the axial direction D1. The divided surface S12a is, for example, formed perpendicular to the divided surface S11a and the divided surface S13a.

[0051] The interstage plate 43 includes divided surfaces S11b, S12b, and S13b formed by being divided at the border line L1. The divided surface S11b is a plane that is formed due to the division at the border line L11, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S11b extends parallel to the divided surface S11a. The divided surface S13b is a plane that is formed due to the division at the border line L13, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S13b is, for example, offset toward the linear passage 62 in the axial direction D1 relative to the divided surface S11b. The divided surface S12b is a plane that is formed due to the division at the border line L12, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S12b connects the divided surface S11b to the divided surface S13b in the axial direction D1. The divided surface S12b is, for example, formed perpendicular to the divided surface S11b and the divided surface S13b.

[0052] The border line L3 that passes through the curved passage 63 and the curved passage 65 divides the inner wall surface 63a and the outer wall surface 63b of the curved passage 63 as well as the inner wall surface 65a and the outer wall surface 65b of the curved passage 65. As a result, the inner wall surface 63a (i.e., the entirety of the inner wall surface 63a from the starting end P2a to the terminal end P3a) and the inner wall surface 65a (i.e., the entirety of the inner wall surface 65a from the starting end P4a to the terminal end P5a) positioned on one side of the border line L3 are formed in the second housing 42. The outer wall surface 63b (i.e., the entirety of the outer wall surface 63b from the starting end P2b to the terminal end P3b) and the outer wall surface 65b (i.e., the entirety of the outer wall surface 65b from the starting end P4b to the terminal end P5b) positioned on the other side of the border line L3 are formed in the interstage plate 43. That is, the inner wall surface 63a and the outer wall surface 63b that form the wall surface of the curved passage 63 are separately formed in the second housing 42 and the interstage plate 43, respectively. The inner wall surface 63a and the outer wall surface 63b that form the wall surface of the curved passage 63 are separately formed in the second housing 42 and the interstage plate 43, respectively.

[0053] The second housing 42 includes divided surfaces S31a, S32a, S33a, S34a, and S35a that are formed by being divided at the border line L3. The divided surface S31a is a plane that is formed due to a division at the border line L31, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S33a is a plane that is formed due to a division at the border line L33, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S34a is a plane that is formed due to a division at the border line L34, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S33a and the divided surface S34a are, for example, offset toward the linear passage 62 in the axial direction D1 relative to the divided surface S31a. The divided surface S32a is a plane that is formed due to a division at the border line L32, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S32a connects the divided surface S31a to the divided surface S32a in the axial direction D1. The divided surface S35a is a plane that is formed due to a division at the border line L35, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S35a connects the divided surface S31a to the divided surface S34a in the axial direction D1. The divided surface S32a and the divided surface S35a are, for example, formed perpendicular to the divided surface S31a, the divided surface S33a, and the divided surface S34a.

[0054] The interstage housing 44 includes divided surfaces S31b, S32b, S33b, S34b, and S35b formed by being divided at the border line L3. The divided surface S31b is a plane that is formed due to the division at the border line L31, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S33b is a plane that is formed due to the division at the border line L33, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S34b is a plane that is formed due to the division at the border line L34, and extends in the vertical direction D2 in the cross-section illustrated in FIG. 5. The divided surface S33b and the divided surface S34b are, for example, offset toward the linear passage 62 in the axial direction D1 relative to the divided surface S31b. The divided surface S32b is a plane that is formed due to the division at the border line L32, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S32b connects the divided surface S31b to the divided surface S32b in the axial direction D1. The divided surface S35b is a plane that is formed due to the division at the border line L35, and extends in the axial direction D1 in the cross-section illustrated in FIG. 5. The divided surface S35b connects the divided surface S31b to the divided surface S34b in the axial direction D1. The divided surface S32b and the divided surface S35b are, for example, formed perpendicular to the divided surface S31b, the divided surface S33b, and the divided surface S34b.

[0055] As a result of the inner wall surfaces and the outer wall surfaces that form the curved passages being formed in separate components as described above, the components (i.e., the first housing 41, the interstage plate 43, the second housing 42, and the interstage housing 44) that form the housing of the compression unit 30 are shaped so as to enable demolding with the axial direction D1 being a demolding direction. A mold herein refers, for example, to a mold for castings. An annular sealing member such as an O-ring may be installed in each of the components at connecting portions of the interstage passage 60. In this case, the occurrence of leakage of the fluid R that flows through the interstage passage 60 is suppressed.

<Operation and Effects>

[0056] The operation and effects described above of the compressor 1 according to this embodiment will now be described together with the problem of a comparative example.

[0057] In a compression unit 130 of the compressor illustrated in FIG. 6, a first housing 141 that accommodates a first impeller 131 is connected to a second housing 142 that accommodates a second impeller 132 by a pipe 170. An interstage passage 160 that introduces the fluid R from the first impeller 131 into the second impeller 132 is formed inside the pipe 170. An interstage plate 143 is disposed between the first housing 141 and the second housing 142. In such configuration in which the pipe 170 is connected to the first housing 141 and the second housing 142, there is the cost for the assembly man-hours of the pipe 170 in addition to the cost of the pipe 170 itself, so that mass production cost tends to be high. Consequently, it is difficult to improve the productivity of the compressor with the compression unit 130.

[0058] It can thus be contemplated to form such interstage passage in the housing of the compression unit. This enables the interstage passage to be formed without any pipes, so that the mass production cost can be suppressed. Additionally, the mass production cost can further be suppressed if the housing can be formed by die-casting, which has a low production cost. However, to form the housing by die-casting, it is necessary for the housing to be shaped to enable demolding. Taking into consideration the flow path of the fluid that passes through the interstage passage, there is a curved passage in one or more locations in the interstage passage that connects the low pressure-side compression stage to the high pressure-side compression stage. Such curved passage can be a factor that inhibits demolding of the housing.

[0059] For example, FIG. 7(a) illustrates a configuration in which the interstage passage 160 having a curved passage 163 is formed inside the housing of the compression unit. In the case in which there is the curved passage 163, it can be contemplated to divide the housing into two components (e.g., a second housing 242 and an interstage housing 244) at a position passing through the curved passage 163 so that the housing is shaped to enable demolding. For example, in a case in which a border line L103 indicating the boundary between the second housing 242 and the interstage housing 244 is set so as to extend linearly in the vertical direction D2 between a terminal end P103a of an inner wall surface 163a and a terminal end P103b of an outer wall surface 163b of the curved passage 163, the border line L103 intersects with the outer wall surface 163b, and divides the outer wall surface 163b into a portion P111 and a portion P112. As a result, the portion P111 of the outer wall surface 163b and the inner wall surface 163a are formed in the same second housing 242. In this case, an overhanging portion B1 is formed in the portion P111, so that the second housing 242 cannot be demolded with the axial direction D1 as the demolding direction.

[0060] On the other hand, as illustrated in FIG. 7(b), in a case in which a border line L203 indicating the boundary between a second housing 342 and an interstage housing 344 extends linearly in the vertical direction D2 so as to pass through a starting end P102a of the inner wall surface 163a and a starting end P102b of the outer wall surface 163b of the curved passage 163, the inner wall surface 163a and the outer wall surface 163b are formed in the same interstage housing 344. In this case, an overhanging portion B2 is formed in the inner wall surface 163a, so that the interstage housing 344 cannot be demolded with the axial direction D1 as the demolding direction. Consequently, the components cannot be formed by die-casting with the border lines L103, L203 illustrated in FIGS. 7(a) and 7(b).

[0061] In contrast, as illustrated in FIG. 8(a), it can be contemplated to set a border line L303 indicating the boundary between a second housing 442 and an interstage housing 444 in the same position as the border line L103 so as not to divide an outer wall surface 263b of a curved passage 263 by the border line L303. That is, it can be contemplated to adjust the shape (degree of curve, etc.) of the outer wall surface 263b such that the outer wall surface 263b does not extend beyond the border line L303. Specifically, it can be contemplated to adjust the position of a starting end P202b of the outer wall surface 263b such that it is on the same side as a terminal end P203b relative to the border line L303. In this case, the starting end P202b and the terminal end P203b of the outer wall surface 263b are positioned on one side of the border line L303, and a starting end P202a and a terminal end P203a of an inner wall surface 263a are positioned on the other side of the border line L303. That is, the inner wall surface 263a and the outer wall surface 263b are separately formed in the second housing 442 and the interstage housing 444.

[0062] Thus, unlike the case in which the inner wall surface 263a and the outer wall surface 263b are formed in one housing, no overhanging portions are formed in the second housing 442 or the interstage housing 444, so that the second housing 442 and the interstage housing 444 are both shaped to enable demolding. Consequently, in the example illustrated in FIG. 8(a), the second housing 442 and the interstage housing 444 can be formed by die-casting. However, in this example, the distance between the outer wall surface 263b and the inner wall surface 263a is not the constant distance d, but a distance d1 that is greater than the distance d due to the adjustment of the shape of the outer wall surface 263b. In this case, changes occur in the cross-sectional area of the curved passage 263. Such changes in the cross-sectional area of the curved passage 263 can affect the flow of the fluid R that flows through the curved passage 263.

[0063] Thus, as illustrated in FIG. 8(b), it can be contemplated to offset the border line L3 indicating the boundary between the second housing 42 and the interstage housing 44 in the axial direction D1. FIG. 8(b) illustrates the same configuration as the compressor 1 according to the embodiment described above. As described above, the border line L31 of the border line L3 extends in the vertical direction D2 between the terminal end P3a of the inner wall surface 63a and the terminal end P3a of the outer wall surface 63b. The border line L33 extends in the axial direction D1 between the starting end P2a of the inner wall surface 63a and the starting end P2a of the outer wall surface 63b, and is connected to the border line L31. The border line L32 extends downward from the border line L33. Dividing the second housing 42 and the interstage housing 44 by such border line L3 causes the inner wall surface 63a and the outer wall surface 63b to be separately formed in the second housing 42 and the interstage housing 44, similarly to the example illustrated in FIG. 8(a). In this case, no overhanging portions are formed in the second housing 42 or the interstage housing 44, so that the second housing 42 and the interstage housing 44 are both shaped to enable demolding. As a result, the components of the compression unit 30 can be formed by die-casting, which has a low production cost, so that productivity can be improved. This makes it possible to suppress the mass production cost.

[0064] Furthermore, as illustrated in FIG. 8(b), setting the border line L3 to be offset in the axial direction D1 eliminates the need to make adjustments such as changing the shape of the inner wall surface 63a or the outer wall surface 63b to match the border line L3. Consequently, the inner wall surface 63a and the outer wall surface 63b can be formed in different housings regardless of the shapes of the inner wall surface 63a and the outer wall surface 63b. As a result, it is possible to avoid the occurrence of situations in which changes occur in each passage cross-section of the curved passage 63 with the change in the shapes of the inner wall surface 63a and the outer wall surface 63b. That is, the distance between the inner wall surface 63a and the outer wall surface 63b can be kept at the constant distance d. This suppresses situations in which pressure loss occurs in the fluid R that flows through the curved passage 63, and suppresses reduction in the performance of the compressor 1.

[0065] In the embodiment described above, the inner wall surface 63a extends linearly and the outer wall surface 63b is curved so as to expand away from the inner wall surface 63a in a cross-section perpendicular to the center line CL of the curved passage 63. This configuration facilitates die-casting of the components with the direction from the outer wall surface 63b toward the inner wall surface 63a as the demolding direction.

[0066] In the embodiment described above, the interstage housing 44 is connected in series to the first housing 41 via the second housing 42 to form the interstage passage 60. This configuration facilitates the forming of the interstage passage 60 by the simple operation of connecting the interstage housing 44, the second housing 42, and the first housing 41 in series.

[0067] In the embodiment described above, the interstage plate 43 is sandwiched between the first housing 41 and the second housing 42 to form the interstage passage 60. This configuration facilitates the forming of the interstage passage 60 by utilizing the interstage plate 43.

[0068] In the embodiment described above, the linear passage 62 includes the first wall surface 62a and the second wall surface 62b that extend linearly and parallel to each other. The first wall surface 62a and the second wall surface 62b are formed in the second housing 42. This makes it possible to demold the second housing 42 with the axial direction D1 in which the linear passage 62 extends as the demolding direction. Consequently, the components can be demolded even with such interstage passage 60 that has the curved passage 63 and the linear passage 62.

[0069] Although in the embodiment described above, the configuration of the curved passage 63 of the interstage passage 60 has been mainly described, the other curved passages 61, 65 may be similarly described. The "curved passage" of the present disclosure may be viewed as any of the curved passages 61, 63, 65. Although in the embodiment described above, the case in which the "linear passage" of the present disclosure is applied to the linear passage 62 has been described, the "linear passage" of the present disclosure may be applied to the other linear passage 64. The "interstage passage" of the present disclosure has at least one curved passage, and it need not have a linear passage.

[0070] Although one embodiment of the present disclosure has been described, the present disclosure is not limited to the embodiment above.

<Variation 1>

[0071] In the example illustrated in FIG. 9, a linear passage 64A that connects a curved passage 63A to a curved passage 65A extends in a direction that is inclined from the vertical direction D2. For example, the linear passage 64A extends in a direction that is at an acute angle to the linear passage 62. Accordingly, the curved passage 65A is disposed in a position offset toward the inlet 42a in the axial direction D1 relative to the curved passage 63A. A border line L3A indicating the boundary between an interstage housing 44A and a second housing 42A has a border line L31A (second border line) instead of the border line L31. The border line L31A extends upward from the border line L33 (first border line), is curved conforming to the inner wall surface 63a so as to be in contact with the terminal end P3a of the inner wall surface 63a, and then extends linearly along the first wall surface 64a to be connected to the border line L35.

[0072] Even in the case in which such interstage passage 60A is formed, the inner wall surface 63a of the curved passage 63A, the first wall surface 64a of the linear passage 64A, and the inner wall surface 65a of the curved passage 65A are formed in the second housing 42A by the second housing 42A and the interstage housing 44A being divided by the border line L3A. Additionally, the outer wall surface 63b of the curved passage 63A, the second wall surface 64b of the linear passage 64A, and the outer wall surface 65b of the curved passage 65A are formed in the interstage housing 44A. By thus forming the wall surface of each passage separately in two components (i.e., the second housing 42A and the interstage housing 44A), the components can be shaped to enable demolding. Furthermore, the components can be shaped to enable demolding regardless of the shape of the wall surface of each passage by offsetting the border line L3A in the axial direction D1, similarly to the embodiment described above. This suppresses situations in which changes occur in the cross-sectional area of the interstage passage 60A, and suppresses situations in which pressure loss occurs in the fluid R that flows through the interstage passage 60A. Consequently, effects similar to those of the embodiment described above can be obtained even with the embodiment illustrated in FIG. 9.

<Variation 2>

[0073] In the example illustrated in FIG. 10, a curved passage 63B is directly connected to the inlet 42a. As a result, the starting end P2a and the terminal end P3a of the inner wall surface 63a and the starting end P2b and the terminal end P3b of the outer wall surface 63b are aligned in the vertical direction D2. A border line L3B indicating the boundary between an interstage housing 44B and a second housing 42B has a border line L31B instead of the border line L31. The borderline L31B extends in the vertical direction D2 between the inner wall surface 63a and the outer wall surface 63b. A lower end of the border line L31B is in the same position as the starting end P2a of the inner wall surface 63a in the vertical direction D2, and is connected to the border line L33 (first border line). An upper end of the border line L31B is in the same position as the terminal end P3a of the inner wall surface 63a in the vertical direction D2, and is connected to the border line L35 (second border line).

[0074] Even in the case in which such interstage passage 60B is formed, the inner wall surface 63a of the curved passage 63B is formed in the second housing 42B and the outer wall surface 63b of the curved passage 63B is formed in the interstage housing 44B by the second housing 42B and the interstage housing 44B being divided by the border line L3B. By thus forming the wall surface of each passage separately in two components (i.e., the second housing 42B and the interstage housing 44B), the components can be shaped to enable demolding. Additionally, the components can be shaped to enable demolding regardless of the shape of the wall surface of each passage by offsetting the border line L3B in the axial direction D1 similarly to the embodiment described above, so that situations in which changes occur in the cross-sectional area of the interstage passage 60B can be suppressed, and situations in which pressure loss occurs in the fluid R that flows through the interstage passage 60B can be suppressed. Consequently, effects similar to those of the embodiment described above can be obtained even with the embodiment illustrated in FIG. 10.

[0075] The present disclosure is not limited to the embodiment described above and the variations, and various other variations are possible. For example, the embodiment described above and the variations may be combined with each other according to the required object and effect. In the embodiment described above, a two-stage compressor has been described as an example. However, the number of stages of the compressor is not limited to two, and may be three or more. Although in the embodiment described above, an example in which the interstage passage 60 is formed by the four components of the first housing 41, the second housing 42, the interstage plate 43, and the interstage housing 44 has been described, it is not necessarily required to be formed of four components. For example, the interstage plate need not extend downward to reach the interstage passage, and the second housing may be directly connected to the first housing. In this case, the interstage passage will be formed by the three components of the first housing, the second housing, and the interstage housing. In the embodiment described above, a pipe for connecting the first housing to the second housing may be separately provided. In this case, the pipe may be bypass-connected to the interstage passage.

[Appendix]

[0076] The present disclosure includes the following configurations.

[0077] A compressor of the present disclosure is [1] "a compressor configured to subject a fluid compressed by a first impeller to further compression by a second impeller, the compressor including: an impeller housing including a first housing accommodating the first impeller, and a second housing accommodating the second impeller; and an interstage component coupled to the impeller housing, and forming, together with the impeller housing, an interstage passage configured to introduce the fluid from the first impeller into the second impeller, wherein the interstage passage includes at least one curved passage, wherein the curved passage includes an inner wall surface that is curved on an inner side in a cross-section passing through a center line of the curved passage, and an outer wall surface that is curved on an outer side in the cross-section, wherein one of the inner wall surface and the outer wall surface is formed in the impeller housing, and wherein another of the inner wall surface and the outer wall surface is formed in the interstage component."

[0078] The compressor of the present disclosure is [2] "the compressor according to [1] above, wherein a border line indicating a boundary between the impeller housing and the interstage component in the cross-section includes a first border line and a second border line between the inner wall surface and the outer wall surface, wherein the first border line extends to intersect a straight line connecting a starting end of the inner wall surface to a starting end of the outer wall surface, and wherein the second border line extends to intersect a straight line connecting a terminal end of the inner wall surface to a terminal end of the outer wall surface, and is directly or indirectly connected to the first border line between the inner wall surface and the outer wall surface."

[0079] The compressor of the present disclosure is [3] "the compressor according to [1] or [2] above, wherein a distance between the inner wall surface and the outer wall surface in a direction perpendicular to the center line is constant at any position along the center line."

[0080] The compressor of the present disclosure is [4] "the compressor according to any one of [1] to [3] above, wherein, in a cross-section perpendicular to the center line of the curved passage, the inner wall surface extends linearly, and the outer wall surface is curved so as to expand from the inner wall surface in a direction opposite the inner wall surface."

[0081] The compressor of the present disclosure is [5] "the compressor according to any one of [1] to [4] above, wherein the interstage component is an interstage housing coupled in series to the first housing via the second housing, wherein the inner wall surface is formed in the second housing, and wherein the outer wall surface is formed in the interstage component."

[0082] The compressor of the present disclosure is [6] "the compressor according to any one of [1] to [4] above, wherein the interstage component is an interstage plate sandwiched between the first housing and the second housing, wherein the inner wall surface is formed in the interstage component, and wherein the outer wall surface is formed in the first housing."

[0083] The compressor of the present disclosure is [7] "the compressor according to any one of [1] to [6] above, wherein the interstage passage further includes a linear passage extending linearly from the curved passage, wherein the linear passage includes a first wall surface connected to the inner wall surface, and a second wall surface connected to the outer wall surface, and wherein the first wall surface and the second wall surface extend parallel to each other in the cross-section passing through the center line, and are formed in the impeller housing."

Reference Signs List

[0084] 

1 Compressor

31 First impeller

32 Second impeller

33 Impeller housing

41 First housing

42, 42A, 42B Second housing

43 Interstage plate (Interstage component)

44, 44A, 44B Interstage housing (Interstage component)

60, 60A, 60B Interstage passage

61, 63, 63A, 63B, 65, 65A Curved passage

61a, 63a, 65a Inner wall surface

61b, 63b, 65b Outer wall surface

62, 64, 64A Linear passage

62a, 64a First wall surface

62b, 64b Second wall surface

CL Center line

d, d1 Distance

L1, L2, L3, L3A, L3B, L11, L12, L13, L21, L22, L31A, L31B, L33, L34, L35 Border line

P1a, P1b, P3a, P3b, P5a, P5b Terminal end

Pa, Pb, P2a, P2b, P4a, P4b Starting end

R Fluid

Claims

1. A compressor configured to subject a fluid compressed by a first impeller to further compression by a second impeller, the compressor comprising:

an impeller housing including a first housing accommodating the first impeller, and a second housing accommodating the second impeller; and

an interstage component coupled to the impeller housing, and forming, together with the impeller housing, an interstage passage configured to introduce the fluid from the first impeller into the second impeller,

wherein the interstage passage includes at least one curved passage,

wherein the curved passage includes an inner wall surface that is curved on an inner side in a cross-section passing through a center line of the curved passage, and an outer wall surface that is curved on an outer side in the cross-section,

wherein one of the inner wall surface and the outer wall surface is formed in the impeller housing, and

wherein another of the inner wall surface and the outer wall surface is formed in the interstage component.

2. The compressor according to claim 1,

wherein a border line indicating a boundary between the impeller housing and the interstage component in the cross-section includes a first border line and a second border line between the inner wall surface and the outer wall surface,

wherein the first border line extends to intersect a straight line connecting a starting end of the inner wall surface to a starting end of the outer wall surface, and

wherein the second border line extends to intersect a straight line connecting a terminal end of the inner wall surface to a terminal end of the outer wall surface, and is directly or indirectly connected to the first border line between the inner wall surface and the outer wall surface.

3. The compressor according to claim 1, wherein a distance between the inner wall surface and the outer wall surface in a direction perpendicular to the center line is constant at any position along the center line.

4. The compressor according to claim 1, wherein, in a cross-section perpendicular to the center line of the curved passage, the inner wall surface extends linearly, and the outer wall surface is curved so as to expand from the inner wall surface in a direction opposite the inner wall surface.

5. The compressor according to claim 1,

wherein the interstage component is an interstage housing coupled in series to the first housing via the second housing,

wherein the inner wall surface is formed in the second housing, and

wherein the outer wall surface is formed in the interstage component.

6. The compressor according to claim 1,

wherein the interstage component is an interstage plate sandwiched between the first housing and the second housing,

wherein the inner wall surface is formed in the interstage component, and

wherein the outer wall surface is formed in the first housing.

7. The compressor according to claim 1,

wherein the interstage passage further includes a linear passage extending linearly from the curved passage,

wherein the linear passage includes a first wall surface connected to the inner wall surface, and a second wall surface connected to the outer wall surface, and

wherein the first wall surface and the second wall surface extend parallel to each other in the cross-section passing through the center line, and are formed in the impeller housing.

Drawing